JP2760041B2 - Fluorescent display device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] In the present invention, a plurality of striped anodes and a plurality of grids are arranged so as to be orthogonal to each other, and a plurality of filaments for thermionic emission are formed in the striped shape. And a graphic type fluorescent display device arranged in parallel with the grid of (1).

[Prior Art] Conventionally, this type of fluorescent display tube has an electrode structure shown in FIG. Here, a plurality of striped anodes 3
(A _{1 to} A ₂₅₆ ) are a plurality of striped grids 2 (G ₁ to
G ₃₃ ) are arranged so as to be orthogonal to each other at a predetermined interval, and the thermoelectrons emitted from the plurality of filaments 1 are accelerated by the grid 2, then collide with the anode 3, and emit phosphors on the surface thereof. To emit light.

The voltage applied to the grid 2 is as shown in FIG.
The same e _c for any of the grids G _{1 to} G ₃₃ ,
This applied voltage is applied to the grid 2 in a time-division manner at the timing shown in FIG. In the example shown in FIG. 6, one screen is scanned by turning on two grids at a time, and by applying a data voltage to the anode 3 at this timing,
Predetermined characters, pictures, and the like are displayed. In the example shown in FIG. 5, the anode A ₂ Yes entering data into the portion of the anode A _2, surrounded by a grid G _2, G ₃ (FIG. 5 when the grid G _2, G ₃ is selected (Indicated by diagonal lines) are emitting light.

[Problems to be Solved by the Invention] However, in the above-mentioned conventional graphic type fluorescent display device, as shown in FIG. 5, a striped grid 2 and filaments 1 for emitting thermoelectrons are arranged in parallel. Therefore, the acceleration of the thermoelectrons emitted from the filament 1 becomes uneven in the arrangement direction of the grid 2. For example, the heat electrons emitted from the filament 1 disposed between the grid G _1, G ₂ shown in Fig. 5, as shown in FIG. 6, e _c of the voltage applied to each grid constant value
Because it is accelerated to the maximum in the region surrounded by the grid G _1, G _2, from the area surrounded by the grid G _2, G _3, grids G
_3, to the region surrounded by the G _4, acceleration in accordance with the distance from the filament 1 is weakened. Therefore, when the pitch of the filaments 1, that is, the interval between the filaments 1 is increased, there is a defect that a phenomenon in which light emission luminance becomes non-uniform in a grid column direction, that is, so-called luminance unevenness occurs.

In order to solve the uneven brightness, the filament 1
Need to be extended at a short interval of about two times the pitch of the grid 2 or the pitch of the grid 2, which increases the manufacturing cost and increases the power consumed by the filament due to the increase in the number of filaments. is there.

The present invention has been made in view of the above problems, and provides a fluorescent display device capable of reducing the number of filaments, reducing manufacturing cost and power consumption, and eliminating luminance unevenness. The purpose is to:

Means for Solving the Problems A fluorescent display device according to the present invention includes a plurality of striped anodes, a plurality of striped grids orthogonal to the anode at a predetermined interval, and a predetermined interval from the anode. A fluorescent display tube having a plurality of filaments opposed in parallel, a means for applying power to the plurality of filaments, a grid drive voltage applying means for applying a time-division scanning voltage to the plurality of grids, An anode voltage applying means for applying an anode voltage for data to the plurality of anodes in accordance with a timing of a scanning signal, wherein a plurality of filaments of the fluorescent display tube have an interval between the plurality of grids. The grid drive voltage applying means divides the plurality of grids into a plurality of groups, and , Wherein drive voltages having different time widths are applied.

[Operation] In the present invention, the filaments are arranged at intervals of an integral multiple of the grid interval. The grid is divided into a plurality of groups, and the driving voltage having a different time width from the grids belonging to each group to the grids belonging to other groups. Is applied. Therefore, a driving voltage having a wider time width than the grid located near the filament, for example, a driving voltage having a time width twice or three times the time width of the grid located near the filament is applied to the grid located far from the filament. Therefore, uneven brightness caused by the distance between the grid and the filament can be eliminated. In addition, since the filaments can be arranged at intervals of, for example, five times or more the interval of the grid, the number of filaments can be reduced, power consumption can be reduced, and the manufacturing cost can be reduced as compared with the related art.

Embodiments FIGS. 1 to 3 show a graphic type fluorescent display tube according to an embodiment of the present invention, FIG. 1 shows an electrode structure of the fluorescent display tube, and FIG. FIG. 3 is a block diagram showing a logic unit and a driver unit necessary for scanning a grid.

As shown in FIG. 1, a striped grid 2 (G ₁
To G ₃₃₎ width is 0.2 mm, the pitch is arranged in parallel to each other at 0.5 mm. In this case, the dimension of the opening between the grids is 0.3 mm. Six filaments 1 are stretched in parallel to the grid 2 at a pitch of 2.5 mm, which is five times the pitch of the grid 2 of 0.5 mm. The anodes 3 are arranged parallel to each other so as to be orthogonal to the grid 2. The number of the anodes 3 is 256. The anodes 3 are formed of an aluminum thin film and a phosphor, and are integrated as an anode substrate. Then, the anodes A _{1 to} A overlapping the openings of the grid 2
Light emitting cells are formed in ₂₅₆ regions. Also, grid 2
And the alignment of the filament 1 is as first filament 1 is located in the middle of the grid G ₁ and the grid G _2, the filament support, by attaching to the anode substrate anode 3 is formed of 256 Do. In this way, a graphic with 256 x 32 light emitting cells
A type of fluorescent display tube is obtained.

The grid voltage applied to the grid 2 of the fluorescent display tube is the shift register 7 and the drivers 8a, 8b, 8c shown in FIG.
Add through.

The grid scanning data is input to the shift register 7 via the data input 9 and has a time width in which the grid 2 can be sequentially selected. The grid scanning data is sequentially output from the 33 output terminals of the shift register 7 by the clock signal input from the clock input 10, and the driver
Transferred to 8a, 8b, 8c. The clock cycle is 200 μs, and as shown in FIG. 2, the output of the shift register 7 is at a low level during a blanking time of 10 μs, and is 190 μs.
During this period, two high-level pulses are output. The output for the grid closest to the filament 1 such as grids G ₁ , G ₂ and G ₆ , G ₇ is the driver 8a
And filaments 1 to 2 like grids G ₃ , G ₅ and G ₃₂
The output for the next closest grid is the driver
To 8b, the output to a grid located farthest from the filament 1 as a grid G _4, G ₃₃ is adapted to be input to the driver 8c.

The pulse width modulation circuit 16 is synchronized with the transfer clock of the shift register 7 and u,
A signal having a time width of v, w is output. The pulse width modulation circuit 16 is constituted by a flip-flop based on the rising edge of the transfer clock of the shift register 7 and generates signals of time widths u, v, w. The time widths u, v, w are, for example, 140
μs, 100 μs, and 10 μs. Therefore, the time width of the voltage actually applied to the grid is 60 μs, 100 μs, and 190 μs.
It is. .

Each of the drivers 8a, 8b and 8c performs an OR operation between an output from the shift register 7 and a signal having a time width of u, v and w from the pulse width modulation circuit 17, respectively.

The voltage generator 11 is provided with a filament voltage E _f and an anode voltage.
Output and E _b, a DC voltage of the grid voltage E _c, and outputs the grid voltage E _c driver 8a, 8b, to 8c. The voltage generating unit 11 is composed of DC-DC / AC converter for generating a filament voltage E _f and anode voltage E _b and the grid voltage E _c.

Grid G ₁ from the driver 8a is a shift register 7, G _2, G ₆
Or each time the output for the G ₇ and the like are input, 2 voltage is e _c
A drive voltage whose time interval between pulses is u is output by a driver.
8b outputs a drive voltage having a voltage of e _c and a time interval between two pulses of v each time an output to the grids G ₃ , G ₅ , G _32, etc. is input from the shift register 7; Each time an output to the grids G ₄ , G _33, etc. is input from, a drive voltage with a voltage of e _c and a time interval between two pulses of w is output. The drive voltage value e _c is a value obtained by subtracting the voltage drop 4 V (maximum) at the driver from the E _c , and in this case, e _c
Becomes 60V.

In the thus configured fluorescent display device, grid scanning data input to the shift register 7 is scanned by a clock signal and transferred from the shift register 7 to the drivers 8a, 8b, 8c. Then, each driver 8a, 8b,
From 8c, the driving voltage of the grid 2 is given to the grid 2 selected by the data. This driving voltage is applied to a grid closest to the filament 1 such as grids G ₁ , G ₂ , G ₆ , and G _{7 for} a time width of 60 μs, and a grid second closest to filament 1 such as grids G ₃ and G _5. those for farthest grid duration 100 [mu] s, the filament 1 as a grid G ₄ that for is duration 190Myuesu. Accordingly, the driving voltage waveform when the driving voltage is sequentially applied to the grids G ₁ , G ₂ , G ₃ ,..., G ₃₃ is a waveform 4 having a time interval u and a time width of 60 μs as shown in FIG. A waveform 5 having a time interval of v and a time width of 100 μs and a waveform 6 having a time interval of w and a time width of 190 μs alternately appear. That is, the time width of the driving voltage for the grid 2 located far from the filament 1 is longer than the time width of the driving voltage for the grid 2 located near the filament. Thereby, the weakening of the acceleration due to being located far from the filament 1 is compensated, and uniform light emission luminance can be obtained. In addition, since the pitch of the filament 1 can be made five times or more the pitch of the grid 2, the number of filaments can be reduced, and the manufacturing cost and the power consumption of the filament can be reduced.

When a display cell having a display capacity of 256 × 32 bits as described in the above embodiment is used, that is, when driving a horizontally long fluorescent display tube, the filament needs to be stretched horizontally to reduce power. Along with this, the scanning grid in the form of a stripe is generally formed at right angles to the filament. However, this has the problem that the time for selecting per unit grid is reduced and the luminance does not increase. However, in this embodiment, the selection time can be increased and the luminance can be increased. While this embodiment with reference to the between the positioning of the filament and grid between the grid G ₁ and the grid G _2, can be superimposed on the grid G ₁ or grid G ₂ obtain the same effect.

FIG. 4 is a diagram showing a circuit section for outputting a waveform for grid scanning according to the second embodiment of the present invention. The graphic type fluorescent display tube used in this embodiment is the same as that in the first embodiment (FIG. 1). 4, the same components as those in FIG. 3 are denoted by the same reference numerals, and description thereof will be omitted.

The reset input 15 of the counter 14 reset signal is input immediately prior to entering the data for the grid G ₁ from the data input 9. After the counter 14 is reset by the reset signal, the counter 14 counts a clock signal corresponding to the scanning of the grid. The 2-bit binary data counted by the counter 14 is input to a data selector 13 such as a 74HC153, and the data selector 13 outputs a four-stage selector signal to the switch unit 12. The switch unit 12 outputs a blanking signal of u, v, w to the drivers 8d, 8e, 8f based on the signal from the data selector 13. The blanking signals of u, v, w are ORed in the driver. In this manner, the switching unit 12 switches the blanking signals u, v, w in accordance with the timing of the grid scanning, so that also in this embodiment, the waveform for the grid scanning shown in FIG. 3 is obtained.

[Effects of the Invention] As described above, when driving a graphic type fluorescent display tube having a striped grid, an anode, and a filament extending parallel to the grid, the present invention provides a driving voltage applied to the grid. By changing the time width according to the distance from the grid filament to the grid, and making the drive voltage time width for the grid far from the filament longer than the grid voltage time width for the grid near the filament, the interval at which the filaments should be arranged is Since it can be further expanded, the manufacturing cost can be reduced, and luminance unevenness can be prevented. Furthermore,
Since the number of filaments can also be reduced, the effect of reducing the power consumption of the filament can be obtained.

[Brief description of the drawings]

FIG. 1 is a schematic diagram showing an electrode structure of a fluorescent display tube according to first and second embodiments of the present invention, FIG. 2 is a diagram showing a driving voltage waveform applied to a grid of the fluorescent display tube, and FIG. FIG. 4 is a block diagram showing a circuit unit for applying a grid voltage according to the first embodiment of the present invention. FIG. 4 is a block diagram showing a circuit unit for applying a grid voltage according to a second embodiment of the present invention. FIG. 1 is a schematic view showing an electrode structure of a conventional fluorescent display tube, and FIG. 6 is a view showing a conventional grid drive voltage waveform. 1; filament, 2; striped grid, 3; striped anode, 4; grid waveform at time interval u, 5; grid waveform at time interval v, 6; grid waveform at time interval w, 7; shift register, 8a to 8f; driver, 9; data input, 10; clock input, 11; voltage generator, 12; switch, 13; data selector, 14; counter, 15; reset input, 16; pulse width modulation circuit

Claims (1)

(57) [Claims] 1. A fluorescent display comprising a plurality of striped anodes, a plurality of striped grids orthogonal to the anode at a predetermined interval, and a plurality of filaments facing the anode in parallel at a predetermined interval. Tubes and
Means for applying power to the plurality of filaments, grid driving voltage applying means for applying a time-division scanning voltage to the plurality of grids, and an anode voltage for data to the plurality of anodes in accordance with a timing of a scanning signal. And a plurality of filaments of the fluorescent display tube, wherein the interval between the plurality of filaments is an integral multiple of the interval between the plurality of grids, and the grid drive voltage applying unit includes the plurality of grid drive voltage applying units. A fluorescent display device, wherein a grid is divided into a plurality of groups, and a driving voltage having a different time width is applied to each group.